A modified polysulfide redox couple, (CH3)4N)2S/((CH3)4N)2Sn, in organic solvent (3-methoxy propionitrile (MPN)), was employed in CdS quantum dots (QDs) sensitized solar cells, and an unprecedented energy conversion efficiency of up to 3.2% was obtained under AM 1.5 G illumination. The QDs were linked to nanoporous TiO2 via covalent bond by using thioglycolic acid (TGA), followed by chemical bath deposition (CBD) in an organic solvent to prepare the QDs-cells, facilitating high wettability and superior penetration capability of the TiO2 films. A very high fill factor (ff) of 0.89 has been observed with the optimized cell.